When capturing and reproducing 3-dimensional images in the prior art, information from one camera of a stereo pair of cameras was depicted as one color (e.g. orange) or band of colors and information from the other camera of the pair was depicted in a complimentary color or color band. When viewing such images through 3-dimensional viewers, such as red/blue glasses, the reproduced image would not be perceived in color.
The orange elements in the picture are only seen through the blue lens, the red lens “washing out” the orange elements. For the same reason, the green-blue elements are only seen through the red lens. Hence, each eye sees only one of the two colored pictures. But because the different colored elements are horizontally shifted in varying amounts, the viewer's eyes must turn inward to properly view some elements, and turn outward to properly view others. Those elements for which the eyes turn inward, which is what the viewer does to observe a close object, are naturally perceived as close to the viewer. Elements for which the viewer's eyes turn outward are correspondingly perceived as distant. Specifically, if the blue lens covers the viewer's right eye, as is generally conventional, then any blue-green element shifted to the left of its corresponding orange element appears to the viewer as close. The element appears closer the greater the leftward shift. Conversely, as a green-blue element is shifted only slightly leftward, not at all, or even to the right of its corresponding red element, that element will appear increasingly more distant from the viewer.
When 3-dimensional images are captured, corresponding points of the left image are displaced from the same points in the right image horizontally. A measurement of the amount of displacement is called “disparity”. In the prior art when stereo images are made, the disparity for all subject matter visible in both images is fixed. In digital images, disparity can be measured in terms of the number of pixels a point on a left image is displayed from the corresponding point in the right image. Fixed focal length lenses are customarily used for the cameras
In an object with zero disparity, the corresponding pixels for the left and right images are perfectly superimposed and the object appears to be located on the screen. Zero disparity objects are seen most clearly when the eyes are crossed just enough to focus on the plane of the screen. Negative disparity objects appear to come out of screen toward the viewer and are seen most clearly when the eyes are more crossed. Positive disparity objects appear to be more distant than the screen and are seen most clearly when the eyes are less crossed.
The eyes cross or uncross in order to get similar image features on or near the fovea of each eye. The “farthest” object that can be seen in an anaglyph is limited by the observers ability to comfortably uncross the eyes. (The usual limit to distant viewing is set by the condition where the eyes look along parallel axes, as when looking at a very distant object such as a star in the night sky. When the eyes attempt to diverge beyond the parallel axes viewing limit, a “wall-eyed” condition exists that is rarely comfortable to the observer.)
Some stereo images cover such a great range of depth and will have such widely varying values (even without a “zoom-in”) that some portions of the image will always be out of range of the observer's ability to see the stereo effects, regardless of how the anaglyph was formed.
Three dimensional techniques are closely related to the psychology and physiology of an observer's cognitive processes. Subtle changes in selection of portions of the spectrum presented to each eye can result in significant changes in the observer's perception. Even when viewing the same 3-dimensional image through the same viewers, different observers may perceive a 3-dimensional image in different ways.
The depth location of the point at which the left and right image points for objects at that distance coincided constitutes a “neutral plane” and when observing a fixed disparity 3-dimensional image, the neutral plane would be found at the surface of the medium of reproduction (i.e. paper or CRT display). Items that appear closer than the medium surface and those points in the image which appear behind the neutral plane would have different disparity. The loss of depth perception when disparity exceeds a certain value generally means that when zooming-in on part of a stereo image pair that disparity will become so great that depth perception will be lost.
In the prior art, there is no way to control an image so as to position it either in front of or behind a neutral plane in a controllable fashion. This limits the ability to create 3-dimensional animations.
In addition, both anaglyphs in stereoscopic optical arrangements are known which permit a user to view images in stereo either using red-blue glasses or separate optical channels for each eye.
Computer systems are also known which attempt to provide a sense of “virtual reality” by which a user perceives a computer generated environment as if the user were immersed in that environment. Typically, these systems permit a measure of interaction between the user and the computer simulated environment. To make the virtual reality environments appear realistic, it is preferable that a user see the environment in three dimensions or, in other words, in a stereo view.
The Problems
One of the serious problems of the prior art is the fact that three dimensional stereo presentations, whether static images or dynamic animations of some sort, typically require much more memory than an XY image that does not contain depth information or suffer from a loss of resolution in the vertical image direction to “line interlace” effects that are necessary to convey “half-image” information to the left eye and “half image” information to the right eye. The size of the files associated with a virtual reality presentation therefore constitute a substantial impediment to the use of those files across networks, especially relatively low speed networks such as the Internet. This is especially true for dynamic, animation presentations where even simple non-stereoscopic-viewing “flick” files (Autodesk *.FLC and *.FLI files), audio-visual-interlace files (Microsoft *.AVI files) and Apple Quicktime VR files can easily occupy 5–100 Mbytes of file space.
It would thus be desirable to have a “small file” size (20–300 Bytes of file space) virtual reality system which would permit rapid file transfer across a relatively low speed network for interactive display with the user at the other end of the network connection.
Another problem with the prior art is that typically, even if the large files can be transferred, the processing required to render a surface texture on a three dimensional wire frame has been excessive. As a result, extremely high performance work stations have been required to do even relatively simple transactions involving virtual reality or stereoscopic presentations.
Further, the generation of wire frames and their subsequent texturing has been an extremely expensive, time consuming process. It would be desirable to be able to capture images, create wire frames and package them for presentation to a user in a rapid; efficient and cost effective manner.